Seminar: Luana Basso

Methane (CH4) is the second most important greenhouse gas. Its atmospheric levels have more than doubled since pre-industrial times and have exhibited highly variable growth rates in recent decades. Despite ongoing efforts to quantify methane sources and sinks using bottom-up and top-down approaches, significant uncertainties remain in the global methane budget. Atmospheric methane loss, primarily caused by the oxidation of hydroxyl radicals (OH), is also a significant source of uncertainty in atmospheric inverse modelling. Uncertainties in the magnitude and temporal variability of OH directly impact the estimation of methane emissions. Therefore, improving estimates of methane emissions at global to regional scales advances our understanding of methane and its climate feedback.In this context, we applied the Jena CarboScope Global Inversion System to estimate global methane surface fluxes from 2000 to 2024. This analysis uses a Bayesian atmospheric inversion framework to optimise surface emissions by combining atmospheric transport modelling with long-term atmospheric methane observations. To evaluate the sensitivity of emission estimates to assumptions about atmospheric loss, we conducted inversions that varied the OH fields, such as using a climatological OH distribution or an interannually varying OH field.This presentation will cover the temporal evolution of global methane emissions over the last two decades, analyse their spatial distribution and regional emission patterns, and evaluate the consistency of the inversion results from the two representations of atmospheric methane loss.